Some service providers use service profile identifiers (SPIDs) to
define the services subscribed to by the Integrated Services Digital Network
(ISDN) device that is accessing the ISDN service provider. The service provider
assigns the ISDN device one or more SPIDs when you first subscribe to the
service. If you are using a service provider that requires SPIDs, your ISDN
device cannot place or receive calls until it sends a valid assigned SPID to
the service provider when accessing the switch to initialize the connection.

Currently, only the DMS-100 and NI-1 switch types require SPIDs. The
AT&T 5ESS switch type may support a SPID, but you should contact your
provider for information on what the SPID must be configured as. Remember that
SPIDs are only required in North America and are configured only if required by
your telco/provider.

The information in this document is based on the software and hardware
versions below.

Cisco IOS® Software Release 12.0

The information presented in this document was created from devices in
a specific lab environment. All of the devices used in this document started
with a cleared (default) configuration. If you are working in a live network,
ensure that you understand the potential impact of any command before using
it.

A SPID is usually a ten-digit telephone number with some optional
numbers. However, service providers may use different numbering schemes. For
the DMS-100 and NI-1 switch types, two SPIDs are assigned, one for each
B-channel. For more information on the SPID format, refer to
Known SPID
Formats.

The format for the SPID configuration command is isdn
spid1 spid-number [ldn]. For
example:

isdn spid1 51255544440101 5554444

The SPID format is shown below:

Three Digit Area Code

Seven Digit Telephone Number

Additional Digits (Optional)

Local Directory Number (LDN) (Optional)

512

5554444

0101

5554444

In this case, 51255544440101 is the SPID number, and the following
seven digit number (5554444) is the optional LDN. Although the LDN is optional,
it must be configured if it is required by the telco.

The LDN is not necessary for establishing outgoing connections, but it
must be specified if you want to receive incoming calls on the B-channel 2. The
LDN is required only when two SPIDs are configured (for example, when
connecting to a DMS-100 or NI1 switch). Each SPID is associated with a LDN.
Configuring the LDN causes incoming calls to the second B-channel to be
answered properly. If the LDN is not configured, incoming calls to the
B-channel 2 will fail.

Sometimes it is beneficial to remove and reenter the SPIDs to clear the
terminal endpoint identifier (TEI) related problems. Follow the steps outlined
below:

Shutdown the BRI using the shutdown
command in the BRI configuration mode.

Remove the SPIDs using the commands no isdn
spid1 and no isdn
spid2.

If possible, reload the router.

The Cisco IOS software normally requests the same TEI it previously
had. However, if the router is reloaded, it will request a new TEI. If you
cannot reload the router, use the clear interface bri
bri_number or clear
controller bri bri_number command.

Some DMS-100 and National ISDN switch installations may be configured
as a "hunt group" whereby all calls are initially forwarded to the primary
number. Under these circumstances, you may not have to configure the LDN. The
telco should be able to provide you more information on whether you need LDNs
for a hunt group. You can determine whether you need LDNs by enabling the
debug isdn q931 command. If the ENDPOINT IDent is
present in the incoming setup message, then the switch is addressing the TEIs
with the EID, instead of the LDN. In this case, the LDN should not be
configured. An example is shown below:

The ENDPOINT IDent above is 0x8183 (in hex) where the 0x81 identifies
the User Service IDentifier (usid) and 83 identifies the Terminal Identifier
(tid). By converting the digits (0x81 or 83) from hex to binary and dropping
the most significant bit, we get a usid=1 and tid=3. Use the show
isdn status command to check which B-channel will answer the
call. For more information on correlating the usid and tid to a particular
B-channel, refer to
Using
the show isdn status Command for BRI
Troubleshooting.

The above situation is also indicated by the debug isdn
q931 messages:

%ISDN-4-INVALID_CALLEDNUMBER: Interface BR1, Ignoring call,
LDN and Called Party Number mismatch
ISDN BR1: Ignoring incoming call, Called Party Number mismatch

If you see the above messages, remove the SPIDs and reenter them
without the LDN.

The telco may configure multiple BRIs in a hunt group using LDNs to
signal which B-channel should answer the call. In such a configuration, the
LDNs must be included in the SPID configuration. The BRIs should be configured
with SPIDs, and each SPID must have a unique LDN number.
If you observe that the second channel for each BRI is not accepting calls,
then verify that you have the LDN configured correctly.

There is a Cisco IOS bug with the id CSCdp20454 in Cisco IOS Software
version 12.0(7)T that displays "SPID NOT valid" in the show isdn
status output. This is a cosmetic bug and should not affect the
performance of your BRI circuit. There is no current workaround, but a Cisco
IOS upgrade should solve this issue.